Dear Authors,

Your manuscript "Geomorphological evolution of landslides near an active normal fault in Northern Taiwan, as revealed by LiDAR and unmanned aircraft system data
" (nhess-2017-227) has been assessed by two reviewers. They raised several critical issues that need to be fixed before publication, and you have provided detailed feedbacks during the NHESS open discussion. Based on this discussion, and my own assessment as Editor, I would like to inform you that it is potentially acceptable for publication in NHESS, provided that you carry out essential revisions suggested by the reviewers.

The paper is interesting, but it falls on the borderline regarding the scope of NHESS. The work focuses more on geomorphology with the long-term development of landforms while less related to hazards. Although the authors discuss some of the activities of the normal fault in recent years, the importance of this work is unclear for the formation and development of the gigantic landslides with the fault activities. I think discussions in this line can be further developed.

Once you have made the necessary corrections, please submit a revised manuscript with point-by-point responses to both reviewers, and highlight all changes made when revising the manuscript. Please ensure you include a detailed rebuttal of any criticisms or requested revisions that you disagreed with. Also, ensure that your revised manuscript conforms to the journal style.

Please note that this editorial decision does not guarantee that your manuscript will be accepted for final publication in NHESS. A decision will be made after the revised version is submitted and evaluated by the same or further reviewers.

We look forward to receiving your revised manuscript soon.

Best regards,
yuichi hayakawa

Dear Authors,

Your revised manuscript has been assessed by the reviewers. Based on their reports, and my own assessment as Editor, I would like to inform you that it is potentially acceptable for publication in NHESS, provided that you carry out some essential revisions.

Once you have made the necessary corrections, please submit a revised manuscript with point-by-point responses to the comments, and highlight all changes made when revising the manuscript. Also, ensure that your revised manuscript conforms to the journal style.

Please note that this editorial decision does not guarantee that your manuscript will be accepted for final publication in NHESS. A decision will be made after the revised version is submitted and evaluated.
We look forward to receiving your revised manuscript soon.

Best regards,
yuichi hayakawa

----

Comments by Editor

The authors have corrected their manuscript following the reviewers’ suggestions. There are some more rooms to revise it as listed below.
* #1-2 and #2-1: The authors now showed that both the UAS-derived DSM and ALS-derived DTM are used for the geomorphological analyses. However, in some cases, the descriptions remain unclear. Therefore, I would like to recommend to further revise the manuscript text and figures to clarify which data were actually used for each analysis. For instance, Figures 6 and 7 provide a hillshade image by ALS-DTM, but the authors state that UAS-DSM is also used for the landslide body area. The data source for profiles in Figure 9 must be from ALS-DTM (I guess), but it is not explicitly shown. By clarifying the more detailed morphological characteristics of the landslide (even if they are significantly modified), it will become possible to argue the issues on the largeness of the landslide size (#2-3a), which can be due to multiple occurrences of sliding.
* Related to the issue above, Figure 6 only shows the hillshade data by ALS-derived DTM. Is it possible to overlay the hillshade by UAS-derived DSM onto this image? Or, as noted below, adding some magnified views of the key morphological features (somewhat like the case in Figure 4) to this or next figure is another option.
* Figure 8 is only mentioned once in the text. This anaglyph may be somewhat useful but not fully because the geomorphological details must have been assessed using the UAS-derived DSM, not only the ALS-DTM. This figure can therefore be omitted. Instead, I would recommend adding more detailed views of key features (main scarp, ridge, etc.) in Figure 7 with their magnified views by UAS-DSM.
* The terms DTM and DEM are mixed. In general, DEM is often an inclusive term, while DTM is more specifically used to indicate the land surface (terrain) data after filtering. I would recommend defining the terms of DSM and DTM when they appears firstly in the manuscript, and replace DEM with DTM thereafter.
* #2-1e: I could not find the detailed descriptions regarding the relative age of the landslide in the main text.
* #2-2a: I could not find the relevant documentation in the manuscript.
* #2-2b: I could not find the relevant documentation regarding the significance of gullies in the manuscript.
* #2-3a: The authors revised the descriptions, but still it is unclear why the two landslides are so large. In page 12 lines 16-17, the authors seem to argue that the multiple occurrences of sliding resulted in the extremely large landslide, but in page 13 lines 20-21, the total volume is compared with the previously-reported landslides. As noted before, detailed morphological characteristics within the landslide body using UAS-DSM should be provided to further argue this issue.
* (#2-3a cont.) Moreover, the way of reproduction of the geological map (new Fig. 5) is unclear. Did the authors performed field validation, or just re-draw the existing geological map on the ALS-DTM image? (P7, L18-20) Please clarify.
* #2-3b: I could not realize what “slope daylight” indicates. Also, the last part of this response is unclear. The newly added description in page 15 lines 18-21 is uncertain: What does “erosion by alluvial processes at the slope toe”? Does this mean that the base-level lowering by fluvial erosion or fault displacement, or both? Please clarify.
* #2-3c: I could not find the relevant documentation in the manuscript.
* #2-4a: The citation to this finding by Lee seems missing in the manuscript. Please provide an appropriate citation (around P2, L27-28?).
* #2-4a: I could not find the relevant documentation in the manuscript.
* #2-4c: Please follow the reviewer’s suggestion regarding the chapters.
* Please follow the styles of NHESS, in particular the references (e.g., P14, L8-9).
* North arrows are missing in Figures 3b-c, 4, 7, 9 (inset), 11, and 12 (inset). That in Figure 6 has an error. The north direction of Figure 8 may also be incorrect.
* Scales are missing in Figures 3b-c, 4f,h,i, 7, and 9 (inset, unknown numbers are shown in the frame).
* Figure 1: Show the summit location and extent area of Tatun Volcano. Please show the extent areas of Figures 3a, 4a-c, 5, and 6.
* Figure 2: I do not see this figure is necessary for this paper. The hillshade image (inset) is already shown in Figure 1, while the IKONOS image does not provide clear appearance of the landslides studies. I would recommend simply removing this figure.
* Figure 3: Please show the location and direction of panels b and c in a.
* Figure 5: Does “study area” mean the extent of Figure 6? If so, please show it as Figure 6.

Dear Authors,
Thank you for revising your manuscript. You have provided appropriate corrections and your paper is almost ready for acceptance. Please check a technical issue below.
Best regards,
yuichi hayakawa

* Figure 7: Please re-order the panels c-g in the left-to-right, top-to-bottom direction (following the "Gutenberg Diagram”).